Method of securing stacked packages against slipping

ABSTRACT

METHOD OF SECURING OBJECTS SUCH AS STACKED PACKAGES OF PAPER, CARDBOARD AND THE LIKE AGAINST SLIPPING, IN WHICH ADJACENT CONTACTING PORTIONS OF SUCH PACKAGES ARE UNITED BY AN ADHESIVE COMPRISING AN AQUEOUS DISPERSION OF A POLYERIZATE OF AN OLEFINIC UNSATURATED COMPOUND WHICH FORMS A FILM AT A TEMPERATURE OF NOT MORE THAN +10*C., IN A HOMOGENEOUS MIXTURE WITH A SUBSTANCE SELECTED FROM THE GROUP CONSISTING OF INORGANIC AND ORGANIC PIGMENTS.

United States Patent 3,598,677 METHOD OF SECURING STACKED PACKAGESAGAINST SLIPPING Eduard Bergmeister, Hubert Wiest, Joseph Heckmaier,

and Heinz Winkler, Burghausen, Upper Bavaria, Germany, assignors toWacker-Chemie G.m.b.H., Munich, Bavaria, Germany No Drawing. Originalapplication Dec. 5, 1966, Ser. No. 598,897. Divided and this applicationFeb. 24, 1969, Ser. No. 801,814 Claims priority, application Germany,Dec. 24, 1965, W 40,595 Int. Cl. B32b 31/00 11.8. C]. 156-276 7 ClaimsABSTRACT OF THE DISCLOSURE Method of securing objects such as stackedpackages of paper, cardboard and the like against slipping, in whichadjacent contacting portions of such packages are united by an adhesivecomprising an aqueous dispersion of a polymerizate of an olefinicunsaturated compound which forms a film at a temperature of not morethan +10 C., in a homogeneous mixture with a substance selected from thegroup consisting of inorganic and organic pigments.

This application is a division of our pending application Ser. No.598,897, filed Dec. 5, 1966, now abandoned.

It is quite a task to prevent stacked goods, which are packed in paperor cardboard, from slipping, i.e. shifting, during loading and shippingaboard vehicles running on or without rails, particularly railroads andtrucks. This problem exists in an increasing degree in the case of goodspacked on fiat pallets, i.e. grid-like supports, on top of each other,in paper bags.

The slippage-preventing agents which have been used heretofore in anattempt to solve the above problem are aqueous alkali silicatesolutions, starch solutions, rubber or natural resin dispersions. Thealkali silicate solutions have the drawback that they have the effect ofsticking so tenaciously that when the stacks are taken down the packingsare damaged by tearing of the paper fibers, or after removal from thestacks films remain on the packing which crumbles easily and thus caneasily contaminate the merchandise when the packages are emptied.Natural resin dispersions have the same drawback. The otheranti-slipping adhesives that have been used heretofore could not beadjusted in their adhesive power to such an extent as to achieve asufficient adhesive effect for reducing slippage in the stacks and atthe same time to prevent damage to the packing due to tearing of thepaper fibers or tearing of the packages when the stacks were removed.

Our invention provides a method of securing stacked packages againstslipping while at the same time permitting such packages to be readilyseparated without tearing or otherwise damaging the packages, such asthe fibers of paper bags when the latter are separated, and withoutcrumbling or shredding in such a way as to contaminate the contents ofthe packages when the latter are opened and in use.

The adhesives which we use as anti-slipping agents are characterized bythe fact that they comprise an aqueous dispersion of an olefinicunsaturated compound which forms a film at a temperature of not morethan +10 C., in admixture with inorganic and/or organic pigments. Thefilm forming temperature, also called white point or lowest temperaturefor film forming (for the definition see R. Houwink and A. I.Stavermann, Chemistry and Technology of Plastics, 4th ed., vol. II/2, p.653) can be obtained from advertising pamphlets of the com 3,598,677Patented Aug. 10, 1971 Ice mercially available polymerizate dispersions,or from the manufacturers of such dispersions, or it can be determinedby applying the dispersion whose film-forming temperature is to be foundin a thickness of 0.3 mm. (measured on the moist, newly applieddispersion) on a glass plate by means of a film-forming apparatus anddrying in a closed space (thermal chamber without air circulation).

Of aqueous dispersions from polymerizates of olefinic unsaturatedcompounds with a film-forming temperature of not exceeding +10 C., thosepreferred are aqueous dispersions of polymerizates and/orcopolymerizates of vinyl acetate with a film forming temperature of +10C.

at the most.

For the adhesives for use as anti-slippage agents according to ourmethod, very suitable are aqueous dispersions of polyvinyl acetate whichcontain plasticizers for polyvinyl acetate like dibutyl phthalate ortricresyl phosphate, and/or soft resins like low-molecular polyesters orpolyvinyl ethers in quantities of 5 to 50 weight percent, preferably 20to 30 weight percent, always referred to the weight of the polyvinylacetate, i.e. which are externally softened dispersions of polymerizatesof vinyl acetate. At times these aqueous dispersions could also bedispersions of copolymerizates of vinyl acetate. Examples ofplasticizers for polyvinyl acetate, besides those named above, areesters of phosphoric acid like tributyl phosphate and diphenylcresylphosphate, esters of phthalic acid like di-2-ethylhexyl phthalateand di-nbutylglycol phthalate, esters of adipic acid like dibutyladipate, dihexyl adipate and dioctyl adipate, esters of sebacic acidlike diethylhexyl sebacate, dibutyl and dihexyl sebacate.

The manufacture of aqueous externally softened dispersions ofpolymerizates and/ or copolymerizates of vinyl acetate with a filmforming temperature not exceeding +10 C. is well known.

Many externally softened polyvinyl acetate dispersions which are wellsuited for use according to our method are commercially available, forinstance from Wacker- Chemie G.m.b.H., Munich, Germany, under the namesVinnapas-Dispersion M 54/25 C, Vinnapas-Disper'sion M 54/25 TC andVinnapas-Dispersion Z 54/20 C. (The word Vinnapas is a registeredtrademark.)

Even more preferred than aqueous externally softened dispersions ofpolymerizates or copolymerizates of vinyl acetate are those aqueousdispersions of copolymerizates of vinyl acetate with a film formingtemperature not exceeding +10 C. which can be called aqueous, internallysoftened polyvinyl acetate dispersions. The polymers in thelast-mentioned kind of dispersions are preferably copolymers of 30 to 90weight percent vinyl acetate and 70 to 10 weight percent vinyl esters ofsaturated aliphatic monocarboxylic acids with 3 to 18 carbon atoms, likevinyl propionate, vinyl laurate or vinyl stearate, esters of saturatedaliphatic alcohols with 3 to 18 carbon atoms, aliphatic unsaturateddicarboxylic acids with 4 carbon atoms like maleic acid dibutyl ester,maleic acid di-2 ethylhexyl ester, fumaric acid dibutyl ester or fumaricacid di-2-ethylhexyl ester, esters of saturated aliphatic alcohols with1 to 18 carbon atoms, of acrylic acid or methacrylic acid, like acrylicacid butyl ester and/or ethylene.

The manufacture of aqueous internally softened polyvinyl acetatedispersions with a film forming temperature of not exceeding +10 C. iswell known. Some examples for copolymerizates of vinyl acetate which areprincipally contained in an aqueous internally softened polyvinylacetate dispersion with a film forming temperature of not more than +10C. are copolymerizates of 60% vinyl acetate and 40% maleic acid dibutylester 60% vinyl acetate and 40% vinyl laurate vinyl acetate and 25%vinyl laurate (Each of the above percentages refers to the total weightof the polymerizate.)

Many internally softened polyvinyl acetate dispersions which are evenmore suitable for application within the limits of the present inventionthan the externally softened polyvinyl acetate dispersions are availablecommercially, for instance from Wacker-Chemie G.m.b.H., Munich, Germany,under the names Vinnapas-Dispersion 50/ 66 H, Vinnapas-Dispersion 50/40VL, Vinnapas-Dispersion A 50/25 VL, Vinnapas-Dispersion Z 53/43 M andVinnapas Dispersion Z 50/25 VL.

One can use mixtures of various externally softened or of variousinternally softened or of externally softened and internally softeneddispersions.

As inorganic or organic pigments one can use all fillers which are notsoluble in water or which are hard to dissolve in water, i.e. whichdissolve not more than 1 weight part in 100 to 1000 weight parts ofwater at 20 C., which are inert towards the polymerizate dispersion, inthe form of more or less dry powders. The following examples may bementioned for such fillers: chalk, light spar, i.e. unburned groundgypsum, kaolin, silicon dioxide produced or precipitated pyrogenicallyin the gaseous phase, wood flour or products similar to wood flour likepeanut shell flour and cork powder. Preferably one uses 200 to 500,especially about 400 weight percent, always referred to the weight ofthe polymerizate, of fillers in the aqueous polymerizate dispersionwhich has a film forming temperature of not more than +10 C. One canalso use mixtures of various fillers.

.Against the above fillers in powder form, however, there are to bepreferred as pigments aqueous dispersions of plastics, particularly ofpolymerizates of olefinic unsaturated compounds with a film formingtemperature of at least +40 C.--because of the decreased danger of thefinished mixtures separating. One can also designate pigments of thiskind as finely dispersed particles used in the form of aqueousdispersions which do not form any film below +40 C., consisting ofpolymerizates of olefinic unsaturated compounds. The upper limit ofdispersions with film forming temperatures of at least +40 C. is notdecisive. For instance, the film forming temperature of thesedispersions may be 150 C. or more.

Among the preferred examples for polymerizates in aqueous dispersions ofpolymerizates of olefinic unsaturated compounds with a film formingtemperature of at least +40 C. may be named: Polyvinyl chloride,polystyrol, copolymerizates of 2 to 70 weight parts vinyl acetate and 98to 30 weight percent vinyl chloride, copolymerizates of 70 to 95 weightpercent styrol and 30 to 5 weight percent butadiene as well ascopolymerizates of 70 to 95 weight percent acrylic nitrile and 30 to 5weight percent butadiene.

The manufacture of aqueous dispersions of polymerizates of olefinicunsaturated compounds with a film forming temperature of at least +40 C.is likewise well known. Some examples of copolymerizates which arecontained in such dispersions, in particular are those of:

60% vinyl chloride and 40% vinyl acetate 85% styrol and 15% butadiene80% acrylic nitrile and 20% butadiene (Each of the above percentagesrefers to the total weight of the polymerizates.)

Many aqueous dispersions of polymerizates of olefinic unsaturatedcompounds with a film forming temperature of at least +40 C. areavailable commercially, for instance from Wacker-Chemie G.m.b.H.,Munich, Germany, under the name Vinnol-Dispersion 45 and from theChemical Works Hills A.G., Marl-Hiils, Germany, under the name Litex SB15. (The name Vinnol as well as the name Litex are registeredtrademarks.)

One can use various aqueous dispersions with a film forming temperatureof at least +40 C.

Preferably the aqueous dispersions with a film forming .4 temperature ofat least +40 C. are used in such quanti ties that 20 to 500, especiallyfrom 60 to 200, weight percent (each time referred to the polymerizatein the aqueous polymerizate dispersion with a film forming temperatureof not more than 10 C.) of the polymerizate of the aqueous polymerizatedispersion with a film forming temperature of at least +40 C. areavailable.

If one uses for pigments aqueous dispersions with a film formingtemperature of at least +10 C., it is particularly helpful to use asaqueous dispersions with a film forming temperature of not more than +10C. no dispersions containing any softeners, but to use internallysoftened polyvinyl acetate dispersions in order to avoid having the filmforming temperature of the dispersion used as a pigment reduced by thesoftener content of the dispersions with a low film forming temperature.

It is preferred that the aqueous polymerizate dispersions with a filmforming temperature of not more than +10 C. as well as the aqueouspolymerizate dispersions with film forming temperatures of at least +40C. should have in each case to weight percent of the dispersed polymerparticles with a diameter of a maximum of 2 microns. Such polymerizatedispersions are usually manufactured in accordance with known methods ofthe so-called dispersion polymerization or by emulsion polymerization.

The manufacture of the adhesives used as anti-slipping agents pursuantto our invention consists of mixing the compounds with each other untila homogeneous mixture is obtained. The temperature and pressure are ofno consequence during mixing and during use of the antislipping agents.The water content of the anti-slipping agents can be adjusted to theviscosity required for each other.

The application of the anti-slipping agents is done by applying saidanti-slipping agents during stacking to the sides of the packages thatget in contact with the sides of other packages, and perhaps also to theside of the pallet which gets in contact with the first layer ofpackages, in each case immediately before the packages are placed uponit. The anti-slipping agents can be applied by spraying on or brushingon, e.g. with a brush or with a roller over the entire surface whereslippage is to be prevented, or only on certain spots on these surfaces,e.g. by point or Wave patterns. The anti-slipping agents areparticularly useful for paper bags, but they can also be usedeffectively on cartons made of full or corrugated cardboard and foldingboxes and other packaging materials made of paper or cardboard.

The anti-slipping agents disclosed herein will bind Within one-half toone whole hour after application, and even if application is made onlyin certain spots the result is safe stacks which will not slip duringloading or transportation. The packages can be separated again easilyand without damage. The film remaining on the packages adheres firmly tothe package surfaces, it is pliable and will not crumble even when thesurfaces are bent.

The parts and percentages shown in the examples below refer in each caseto the Weight. The percentages are calculated in each case for the totalweight of the dispersions, provided nothing to the contrary is stated.

EXAMPLE 1 67 parts of a 50% aqueous dispersion of a copolymerizate of 60parts vinyl acetate and 40 parts vinyl laurate, with a film formingtemperature of 0 0., containing as a dispersion agent about 3 percentpolyvinyl alcohol with the saponification number (milligrams KOH,required for splitting off and neutralizing the remaining acetyl groupsin 1 g. polyvinyl alcohol) of and wherein at least 80% of the dispersedpolymer particles have diameters within the range from 1 to 2 microns,are stirred with 133 parts light spar which were first mixed with 75parts wat un il a homogeneous mix is obtained.

The anti-slipping agent obtained in this manner is properly dilutedbefore use with three parts of water per one part of anti-slippingagent.

EXAMPLE 2 70 parts of an aqueous dispersion with a film formingtemperature of below C. containing 43% polyvinyl acetate, as a softener11% dibutyl phthalate and as a dispersion agent about 3% polyvinylalcohol with a saponification number of 140, and wherein at least 80% ofthe dispersed polymer particles have diameters in the range from 1 to 2microns, are stirred with 140 parts chalk which were first mixed with100 parts water until a homogeneous mix is obtained.

The anti-slipping agent obtained in this manner can be diluted beforeuse with up to 4 parts water per part of anti-slipping-agent.

EXAMPLE 3 100 parts of an aqueous dispersion of a copolymerizate with afilm forming temperature of 0 C., of 75 parts vinyl acetate and 25 partsvinyl laurate, containing as a dispersion agent about 3% of aphenolpolyoxethylene glycol ether available commercially as anemulsifier and 0.3% sec. sodium C -alkyl-sulfonate, and wherein at least80% of the dispersed polymer particles have a diameter of about 0.1micron, are stirred with 80 parts of an aqueous dispersion with a filmforming temperature of over 100 C., containing 45% polyvinyl chlorideand as a dispersion agent 2% sodium lauryl sulfate, and wherein at least80% of the polymer particles have a diameter of less than 0.5 micron;and with 550 parts of water, to form a homogeneous mixture.

EXAMPLE 4 100 parts of the dispersion described in Example 3 as adispersion with a film forming temperature of 0 C. are stirred with 80parts of a 45% aqueous dispersion of a mixed polymerizate with a filmforming temperature of 60 C. containing 60 parts vinyl chloride and 40parts vinyl acetate, and containing as a dispersion agent 2% sodiumlauryl sulfate, and wherein at least 80% of the polymer particles have adiameter of less than 0.5 micron; and with 500 parts of water, until ahomogeneous mixture is formed.

EXAMPLE 5 100 parts of an aqueous dispersion with a film formingtemperature of +6 C. containing 50% of a copolymerizate of 60 partsvinyl acetate and 40 parts maleic acid dibutyl ester and as a dispersionagent 0.5% polyvinyl alcohol with a saponification number of 140, 0.33%of a mixture of 1 part sodium cetyl sulfate and 1 part sodium stearylsulfate and 0.75% of a cetyl polyoxy ethylene glycol ether with anaverage of about 10 oxyethylene units per molecule, and wherein at least80% of the dispersed polymer particles have a diameter in the range from0.5 to 2 microns, are stirred with 100 parts of an aqueous dispersionwith a film forming temperature of over 100 C. which contains 50% of acopolymerizate of 85 parts styrol and parts butadiene and as adispersion agent 4% sec. sodium C '=alkyl sulfonate, and wherein atleast 80% of the dispersed polymer particles have a diameter of below0.5 micron; and with 800 parts of water, until a homogeneous mixture isformed.

EXAMPLE 6 100 parts of the dispersion described in Example 3 as adispersion with a film forming temperature of 0 C. are stirred with 100parts of an aqueous dispersion with a film forming temperature of over100 C. containing 50% of a copolymerizate of 80 parts acrylonitrile andparts butadiene and as a dispersion agent 4% sec. sodium C =alkylsulfonate, and wherein at least of the dispersed polymer particles havea diameter of less than 0.5 micron: and 1000 parts of water, until ahomogeneous mixture is formed.

The mixtures produced in accordance with Examples 1 through 6 are usedin such a manner that 4 squirts (each about 3 ml.) of each mixture areapplied from a polyethylene spray bottle by hand pressure to a paper bagand the next bag is laid on the treated side of the first bag. After 40hours the bags are separated. No damage to the paper occurs, and thefilms of the adhesive will not crumble off even if the paper is creased.

All temperatures shown above and in the appended claims, in front ofwhich there is no plus sign represent temperatures above 0 C. if thereis no minus sign in front of them and if the temperature shown is not 0C.

The invention claimed is:

1. Method of securing stacked packages of paper, cardboard and the likeagainst slipping, wherein adjacent contacting portions of said packagesare united by an adhesive comprising a first aqueous dispersion of apolymerizate or copolymerizate of vinyl acetate, said first dispersionhaving a film forming temperature of not more than 10 C., in being ahomogeneous mixture with a second aqueous dispersion of an organicpigment consisting essentially of a polymerizate of an olefinicunsaturated compound, said second dispersion having a film formingtemperature of at least +40 C. I

2. Method according to claim 1, in which said first aqueous dispersioncomprises polyvinyl acetate and a plasticizer for said polyvinyl acetatein a quantity of 10 to 50 weight percent referred to the weight of thepolyvinyl acetate.

3. Method according to claim 1, in which said first aqueous dispersionis an aqueous internally softened polyvinyl acetate dispersion.

4. Method according to claim 1, in which the organic pigment is presentin a quantity of 20 to 500 weight percent calculated as polymerizate andreferred to the weight of the polymerizate in the first aqueouspolymerizate dispersion.

5. Method according to claim 1, wherein 80 to weight percent of each ofthe dispersed polymerizate consists of polymer particles which have adiameter of not more than 2 microns.

6. Method according to claim 1, in which said pigment is in the form ofa powder in a quantity of 200 to 500 weight percent referred to theweight of the polymerizate in the aqueous dispersion.

7. Method according to claim 1, in which an internally softenedpolyvinyl acetate dispersion with a film forming temperature of not morethan -+10 C. is homogeneously mixed with a polymerizate of an olefinicunsaturated compound having a film forming temperature of at least +40C.

References Cited UNITED STATES PATENTS 3,036,977 5/1962 Koch et a1.156-327 3,268,496 8/1966 Germain 156-327 3,301,809 1/1967 Goldberg etal. 26029.6 3,365,409 1/1968 Lanthier 156327 3,419,641 12/1968 Peterkinet al. 156327 3,444,037 5/ 1969 Armour 15 6-327 CARL D. QUARFORTH,Primary Examiner S. J. LECHERT, JR., Assistant Examiner US. Cl. X.R.

